Large commercial aircraft that service hundreds of passengers at a time is typically equipped with a service station, or galley, that is used to house all of the equipment and foods for the passengers' and crew's meal and beverage service. The galley is typically a built in structure that is part of the aircraft, designed to meet the needs of the particular aircraft while adhering to the goals and limitations of weight conservation and space efficiency that is critical to all aircraft. Each galley will typically have ovens to heat food, beverage makers to make coffee and espresso, waste disposal areas, and chillers or coolers to store the meals and perishables until they are ready to be served. These chillers or coolers and typically built into the galley, and must be able to store milk, fruits, frozen meals, and other types of perishables at a temperature that allows the food to be safely served after several hours in flight.
In order to meet the health and safety requirements to preserve perishable foods for consumption by passengers during an airlines in-flight catering service, a storage structure such as a galley has to have a level of thermal insulation that is capable of resisting conductive losses to a level that will allow the galley to meet or exceed the manufacturer's and airworthiness authority's requirements for the safe storage of food stuffs over a specific period, using the galley chilling system provided for that galley. The minimum thermal resistance level of a food storage structure is usually specified as an average value for the entire monument, which takes into account losses through cold bridges between the chilled compartments and the warmer exterior ambient temperatures.
These cold bridges typically take the form of metallic items such as floor fittings, edge members, potted inserts, bobbins, embedded and mouse hole blocks, sliding tables, door hinges, latches, and access panels, as well as poorly insulated nonmetallic areas such as recessed panels, cut outs and cable passes. Each of these types couplings and structures conduct heat into the galley, which must be removed by the refrigeration unit. The amount of heat that is allowed across these structures is dependent upon a property called the thermal resistance. The average thermal resistance performance of a chilled storage structure such as a chiller or cooler equates to the capability of the nonmetallic panel that forms the housing, less any losses through cold bridges and poorly insulated areas.
Galley panels made from a 13 mm (½″) Nomex® cored pre-impregnated structural panel is insufficient to maintain aircraft galley chilled compartments at or below the required safe temperature for perishable food stuffs. Therefore, in order to improve the monument's thermal capability to allow perishables to be stored safely, either the thickness of the panel has to be increased or supplemental insulation has to be added to the structure.
In addition to the thermal losses, the reduction of intrusive noise into an aircraft cabin, usually produced by the routine operation of an in-flight airline catering service, is a prime objective of the aircraft manufacturers. Much of this noise can be generated by galley insert equipment (“GAINS”), such as ovens, refrigerators, beverage makers, and the like, along with the incumbent noise introduced by the cabin crew preparing meals. That is, the preparing of meals includes removing standard meal boxes from their compartments, filling meal carriers for ovens, opening and closing compartment doors, moving carts from their compartments, and so on. Aircraft manufacturers seek to reduce the overall noise in the passenger cabin by providing various sound attenuation mechanisms such as using sound absorbing materials. By incorporated such materials into the galley surfaces, the acoustic levels inside the cabin due to the preparation and clean-up of the beverage and meal service can be significantly reduced.